From Wikipedia

Bronze Age China

Historians disagree about the dates that should be attached to a “Bronze Age” in China. The difficulty lies in the term “Bronze Age” itself, as it has been applied to signify a period in European and Middle Eastern history when bronze tools replaced stone tools, and were later replaced by iron ones. In those places, the medium of the new “Age” made that of the old obsolete. In China, however, any attempt to establish a definite set of dates for a Bronze Age is complicated by two factors: the arrival of iron smelting technology and the persistence of bronze in tools, weapons and sacred vessels. The earliest bronze artifacts are found in the Majiayao culture site (between 3100 and 2700 BCE), and from then on the society gradually grew into the Bronze Age

Bronze metallurgy in China originated in what is referred to as the Erlitou (also Erh-li-t’ou) period, which some historians argue places it within the range of dates controlled by the Shang dynasty. Others believe the Erlitou sites belong to the preceding Xia (also Shia) dynasty. The U.S. National Gallery of Art defines the Chinese Bronze Age as the “period between about 2000 BC and 771 BCE,” a period that begins with Erlitou culture and ends abruptly with the disintegration of Western Zhou rule. Though this provides a concise frame of reference, it overlooks the continued importance of bronze in Chinese metallurgy and culture. Since this is significantly later than the discovery of bronze in Mesopotamia, bronze technology could have been imported rather than discovered independently in China.

Chinese pu bronze vessel with interlaced dragon design, Spring and Autumn Period (722–481 BCE)

Iron is found in the Zhou period, but its use is minimal. Chinese literature dating to the 6th century BCE attests a knowledge of iron smelting, yet bronze continues to occupy the seat of significance in the archaeological and historical record for some time after this. Historian W. C. White argues that iron did not supplant bronze “at any period before the end of the Zhou dynasty (481 BCE)” and that bronze vessels make up the majority of metal vessels all the way through the Later Han period, or through CE 221.

The Chinese bronze artifacts generally are either utilitarian, like spear points or adze heads, or ritualistic, like the numerous large sacrificial tripods. However, even some of the most utilitarian objects bear the markings of more sacred items. The Chinese inscribed all kinds of bronze items with three main motif types: demons, symbolic animals, and abstract symbols. Some large bronzes also bear inscriptions that have helped historians and archaeologists piece together the history of China, especially during the Zhou period.

The bronzes of the Western Zhou period document large portions of history not found in the extant texts, and often were composed by persons of varying rank and possibly even social class. Further, the medium of cast bronze lends the record they preserve a permanence not enjoyed by manuscripts. These inscriptions can commonly be subdivided into four parts: a reference to the date and place, the naming of the event commemorated, the list of gifts given to the artisan in exchange for the bronze, and a dedication. The relative points of reference these vessels provide have enabled historians to place most of the vessels within a certain time frame of the Western Zhou period, allowing them to trace the evolution of the vessels and the events they record.